I wanted to share the only Haskell resource that has ever worked for me.

While it uses older Haskell98 as its standard, or to be even more precise Hugs98 subset, it is to my knowledge the easiest to follow presentation of the Haskell language. Devoid of self-praising attitude that annoyed me in many other books and tutorials, instead focused on presenting the basics of functional programming while teaching you about basic mathematical constructs.

You can find book website here: http://homepages.cwi.nl/~jve/HR/ . It contains source code and solutions to exercises along with errata.

Consider buying physical version if you find it to your liking. I'm not by any means related to authors or publisher, I do feel that it's a nice reciprocation for their kindness and making book available for free.